solution: day4

src/bin/04.rs

@@ -0,0 +1,57 @@
+use crypto::digest::Digest;
+use crypto::md5::Md5;
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let key = input.trim().as_bytes();
+    let mut hasher = Md5::new();
+    for x in 0..std::u64::MAX {
+        hasher.input(key);
+        hasher.input(x.to_string().as_bytes());
+
+        let mut output = [0; 16];
+        hasher.result(&mut output);
+
+        let first_five = output[0] as u32 + output[1] as u32 + (output[2] >> 4) as u32;
+        if first_five == 0 {
+            return Some(x as u32);
+        }
+        hasher.reset();
+    }
+    None
+}
+pub fn part_two(input: &str) -> Option<u32> {
+    let key = input.trim().as_bytes();
+    let mut hasher = Md5::new();
+    for x in 0..std::u64::MAX {
+        hasher.input(key);
+        hasher.input(x.to_string().as_bytes());
+
+        let mut output = [0; 16];
+        hasher.result(&mut output);
+
+        if output.starts_with(&[0,0,0]) { return Some(x as u32)}
+        hasher.reset();
+    }
+    None
+}
+fn main() {
+    let input = &aoc::read_file("inputs", 4);
+    aoc::solve!(1, part_one, input);
+    aoc::solve!(2, part_two, input);
+}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_part_one() {
+        // let input = aoc::read_file("test_inputs", 4);
+        let input = "abcdef";
+        assert_eq!(part_one(&input), Some(609043));
+    }
+    #[test]
+    fn test_part_two() {
+        // let input = aoc::read_file("test_inputs", 4);
+        // let input = "abcdef";
+        // assert_eq!(part_two(&input), None);
+    }
+}